Zipcode-based classification

In recent years, interest has grown in parsing voters’ attitudes by their community’s degree of urbanicity or rurality. The Marquette Law Poll asks respondents, “Would you describe the place where you live as urban, suburban or rural?” If necessary, we clarify, “Urban is a big city like Milwaukee, Madison or Green Bay. Suburban is a built up place close to a big city and rural is less built up with fewer people and further away from a big city.”

This self-description is interesting, but it’s not entirely clear what it tells us. Each individual defines those terms in their own mind, and many places don’t fall neatly within the three offered categories.

Using the USDA Rural-Urban Commuting Area Codes (RUCA) I have created an alternative, objective zip-code based geography classification for the Marquette Law Poll. “Objective” does not mean “correct.” It simply means that the same data-based methodology has been uniformly applied to each case.

The original USDA RUCA classification is based on both a zip code’s location (e.g. within a census-defined urbanized area or urban cluster) as well as how its residents commute. Because it is a measure of economic activity, RUCA does not further distinguish between central cities and suburbs within metro areas. Obviously, the city-suburb distinction is crucial for political research, so I add a new principal city code. This consists of all zip codes with a majority of their population inside a core-based statistical area’s principal city (or cities).

With my addition of principal cities, here are all 11 RUCA categories along with the number of Wisconsin zip codes in each. I combine the 11 RUCA codes into 5-category, 4-category, and 3-category alternatives as indicated. The 5, 4, and 3-category RUCA breakdowns are available as crosstab variables on the Marquette Law Poll interactive crosstab web application.

zips ruca11 ruca5 ruca4 ruca3
74 Principal city Principal city Principal city Urban areas
110 Suburban core Suburban core Suburban core Urban areas
136 Strongly tied to urban area Exurbs and large towns Exurbs and large towns Exurbs and large towns
20 Weakly tied to urban area Exurbs and large towns Exurbs and large towns Exurbs and large towns
30 Large town Exurbs and large towns Exurbs and large towns Exurbs and large towns
41 Strongly tied to large town Exurbs and large towns Exurbs and large towns Exurbs and large towns
6 Weakly tied to large town Exurbs and large towns Exurbs and large towns Exurbs and large towns
81 Small town Small town Rural and small towns Rural and small towns
39 Strongly tied to small town Small town Rural and small towns Rural and small towns
15 Weakly tied to small town Small town Rural and small towns Rural and small towns
222 Isolated rural Isolated rural Rural and small towns Rural and small towns

Maps

Click through these tabs to view which zip codes make up each category, for each RUCA level.

RUCA 11

RUCA 5

RUCA 4

RUCA 3

Population

Use the tabs below to see the population of each RUCA category.

RUCA 11

Wisconsin population
pop pct
Principal city 1,961,107 34%
Suburban core 1,794,118 31%
Strongly tied to urban area 537,919 9%
Weakly tied to urban area 33,233 1%
Large town 314,473 5%
Strongly tied to large town 87,405 2%
Weakly tied to large town 9,755 0%
Small town 486,196 8%
Strongly tied to small town 83,170 1%
Weakly tied to small town 22,532 0%
Isolated rural 448,506 8%

RUCA 5

Wisconsin population
pop pct
Principal city 1,961,107 34%
Suburban core 1,794,118 31%
Exurbs and large towns 982,785 17%
Small town 591,898 10%
Isolated rural 448,506 8%

RUCA 4

Wisconsin population
pop pct
Principal city 1,961,107 34%
Suburban core 1,794,118 31%
Exurbs and large towns 982,785 17%
Rural and small towns 1,040,404 18%

RUCA 3

Wisconsin population
pop pct
Urban areas 3,755,225 65%
Exurbs and large towns 982,785 17%
Rural and small towns 1,040,404 18%

Data accuracy

The data underlying the USDA’s original 2010 RUCA codes is growing stale. Updated classifications will be available sometime after the 2020 census. Fortunately (for our purposes), Wisconsin’s population and economic patterns have changed very little this decade, with the important exception of the Madison metro area. I expect Madison’s footprint to expand significantly in the 2020 RUCA vintage. The rest of Wisconsin will probably look much the same.

RUCA vs self-reported geography

RUCA codes do not line up perfectly with self-reported urban, suburban, or rural status. The following tables show the self-reported geography by RUCA classification, for each level of RUCA.

It seems to me that respondents use a sort of “backporch” test to answer the urban/suburban/rural question. If the view from their house contains fields, they call it “rural.” The RUCA classification, on the other hand, is fundamentally an economic judgement. People who live in visually “rural” areas that are nonetheless economically intertwined with larger metros are considered part of a metro area.

RUCA 11

Self-reported geography vs. RUCA geography classification
Marquette Law School Poll, 2015-2020
Urban Suburban Rural Don't know n
Principal city 50% 34% 15% 1% 8,289
Suburban core 21% 59% 19% 1% 8,196
Strongly tied to urban area 8% 21% 71% 1% 2,511
Weakly tied to urban area 4% 9% 87% 0% 201
Large town 20% 29% 50% 1% 1,452
Strongly tied to large town 8% 9% 83% 0% 479
Weakly tied to large town 8% 2% 87% 2% 73
Small town 16% 14% 69% 1% 2,252
Strongly tied to small town 12% 8% 80% 0% 391
Weakly tied to small town 8% 10% 81% 2% 108
Isolated rural 7% 6% 86% 1% 2,297

RUCA 5

Self-reported geography vs. RUCA geography classification
Marquette Law School Poll, 2015-2020
Urban Suburban Rural Don't know n
Principal city 50% 34% 15% 1% 8,289
Suburban core 21% 59% 19% 1% 8,196
Exurbs and large towns 11% 21% 66% 1% 4,716
Small town 15% 13% 71% 1% 2,751
Isolated rural 7% 6% 86% 1% 2,297

RUCA 4

Self-reported geography vs. RUCA geography classification
Marquette Law School Poll, 2015-2020
Urban Suburban Rural Don't know n
Principal city 50% 34% 15% 1% 8,289
Suburban core 21% 59% 19% 1% 8,196
Exurbs and large towns 11% 21% 66% 1% 4,716
Rural and small towns 12% 10% 78% 1% 5,047

RUCA 3

Self-reported geography vs. RUCA geography classification
Marquette Law School Poll, 2015-2020
Urban Suburban Rural Don't know n
Urban areas 36% 46% 17% 1% 16,485
Exurbs and large towns 11% 21% 66% 1% 4,716
Rural and small towns 12% 10% 78% 1% 5,047

RUCA and issues

RUCA codes line up nicely with lifestyle questions that we expect to vary along the rural-urban continuum. For example, 47 percent of rural respondents are deer hunters, compared with 38 percent from small towns, 36 percent from exurbs and large towns, 23 percent from the suburbs, and 21 percent from principal cities.

Are you or any member of your household a deer hunter?
Marquette Law Poll of Wisconsin registered voters, fall 2019
Yes, respondent Yes, another household member Yes, both respondent and another household member No, nobody in household Don't know n
Principal city 16% 10% 5% 68% 0% 468
Suburban core 19% 12% 4% 65% 1% 471
Exurbs and large towns 22% 14% 14% 50% 0% 258
Small town 25% 11% 13% 50% 0% 149
Isolated rural 34% 12% 13% 41% 0% 133

 

Democratic strength is concentrated in principal cities, where they have a 22-point advantage over Republicans (including independents who lean to either party). Combining all polls taken after 2016, Republicans have a 7-point partisan identification advantage in the suburbs, a 14-point advantage in exurbs and large towns, a 9-point advantage in small towns, and a 16-point lead in isolated rural areas.

 

Party ID by RUCA code
Wisconsin registered voters, 2017-2020
Republican Independent Democrat n
Principal city 34% 9% 56% 4,917
Suburban core 49% 8% 42% 5,039
Exurbs and large towns 53% 8% 39% 2,882
Small town 50% 9% 41% 1,623
Isolated rural 52% 11% 36% 1,358

 

Donald Trump’s weakness in the suburbs is clear. Despite a 7-point Republican identification advantage in the suburbs, Trump is tied with Joe Biden among suburban voters when all 2020 polling is combined.

Trump does best with voters from isolated and rural areas, where he has a 17-point lead over Biden. He has an 8-point lead in exurbs and large towns, along with a 6-point lead in small towns.

 

Biden vs Trump by RUCA code
Wisconsin registered voters, all 2020 polls through August
Joe Biden Donald Trump Neither (VOL) n
Principal city 58% 33% 5% 1,460
Suburban core 46% 46% 5% 1,458
Exurbs and large towns 43% 51% 2% 889
Small town 42% 48% 3% 475
Isolated rural 38% 55% 3% 385